1. Field of the Invention
The present invention relates to 3D-inkjet printing methods and suitable inkjet fluid sets. More specifically the present invention relates to the making of 3D-objects and flexographic printing forms.
2. Description of the Related Art
In inkjet printing, tiny drops of ink or fluid are projected directly onto a receiver surface without physical contact between the printing device and the ink-receiver. The printing device stores the printing data electronically and controls a mechanism for ejecting the drops image-wise. Printing is accomplished by moving a print head across the ink-receiver or vice versa or both.
Flexography is commonly used for high-volume runs of printing on a variety of supports such as paper, paperboard stock, corrugated board, films, foils and laminates. Packaging foils and grocery bags are prominent examples. Flexographic printing forms are today also made by digital imaging, which includes not only laser recording on flexographic printing form precursors, but also inkjet printing as disclosed, for example, in EP 1449648 A (KPG), EP 1428666 A (AGFA) and US 2006055761 (AGFA).
Three-dimensional inkjet printing is a relatively speedy and flexible printing method for the production of prototype parts, tooling and rapid manufacturing of three-dimensional complex structures directly from a CAD file.
Radiation curable compositions for use in three-dimensional printing methods of complex structures are disclosed by WO 2004/096514 (OBJET GEOMETRIES).
U.S. Pat. No. 5,387,380 (MIT) and U.S. Pat. No. 6,036,777 (MIT) disclose methods for forming three-dimensional images, to be used in “rapid prototyping”, wherein the method includes the steps of (i) depositing a first layer of a powder material in a confined region, (ii) depositing a binder material to selected regions of the layer of powder material to produce a layer of bonded powder material at selected regions, (iii) repeating steps (i) and (ii) a selected number of times to produce successive layers of selected regions of bonded powder so as to form the desired prototype. The unbounded powder material is then removed.
Three-dimensional objects have been made which exhibit different colours, but usually all 3D-objects have uniform physical properties for, e.g., hardness or elasticity. In EP A (AGFA) advantages are high-lighted for preparing flexographic printing plates by printing two materials with different elasticity or hardness on a receiving layer. However, problems, such as insufficient adhesion and defects in image quality, can be observed in changing from a “soft, elastic” inkjet ink to a “hard, inelastic” inkjet ink or vice versa. A compromise can then usually be found in changing, for example, the “soft, elastic” inkjet ink to a harder and less elastic inkjet ink, but resulting in the fact that the maximal soft and elastic properties are not attained.
A change in hardness of the top layer of a flexographic printing plate is generally desirable for obtaining a good printing quality when a change in the type of support to be printed upon occurs. One way to approach this is to develop and replace the inkjet fluid or ink used in the printer and print head by a more appropriate inkjet fluid or ink. However, changing of inkjet fluid or ink tends to be very time consuming and is not really a viable solution for an industrial printing environment.
It would be desirable to be able to prepare three-dimensional objects and flexographic printing forms wherein the physical properties, such as flexibility, hardness and elongation at break, can be easily altered without causing problems of adhesion and image quality or without a time-consuming replacement of an inkjet fluid or ink.